section 13

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apvg1997
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section 13
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2015-11-15 18:35:12
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section 13
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  1. sarcolemma
    muscle plasma membrane
  2. sarcoplasm
    cytoplasms of a muscle cell
  3. myo, mys, and sarco refer to what?
    muscle
  4. epi
    around
  5. peri
    between
  6. fascle
    bundle of muscle fibers
  7. muscle fibers
    • long, cylindrical cell
    • multiple nuclei underneath sarcoloma
  8. myofibrilis
    • (muscle fibers)
    • contractile elements
    • most of muscle volume
  9. sarcomeres
    • smallest contractile unit of muscle
    • 2 types- thick and thin
  10. ACTIN
    • thick filaments
    • thin filaments
  11. thick filaments
    • extend the entire length of an A band
    • myosin
  12. thin filaments
    • extend across the I band and partway into the A band
    • actin, tropomyosin and troponin
  13. Z disc
    • or Z line
    • coin shaped sheet of proteins (connnectins) that anchors the thin filaments and connects myofibrils to one another
  14. thin filaments do not what?
    overlap thick filaments in the lighter H zone
  15. tropomysosin and troponin
    regulatory subunits bound to actin
  16. sliding filament model of contraction?
    • in relax state, thin and thick filaments overlap only slightly
    • upon stimulation, myosin heads bind to actin (cross bridge formation) and sliding begins
    • think filaments slide past thick filaments
    • overlap of actin and myosin filaments increases
  17. skeletal muscle contraction
    • 1. be stimulated by nerve ending
    • 2.produce an electrical current, or action potential, along the sarcolemma
    • 3.have a ruse in intracellular Ca levels
  18. action potential
    electrical current
  19. somatic
    in the body
  20. neuron
    nerve cell
  21. skeletal muscles are stimulated by what?
    motor neurons of the somatic nervous system
  22. each muscle is served by?
    one nerve containing numerous neurons
  23. motor unit?
    muscle fibers
  24. each neuron controls what?
    a number of muscle fibers (motor unit)
  25. what is acetyl choline?
    a neurotransmitter
  26. nerve stimulus of skeletal muscle (phase 1)
    • Acetyl Choline is released from presynaptic neuron
    • ACh binds its receptors at the postsynaptic motor end plate
    • binding opens chemically gated channel
    • Na+ diffused through channel and the interior of sarcolemma becomes less negative (depolarization)
    • depolarization leads to and action potential that spreads in all directions across the sarcolemma
  27. depolarization
    when Na+ diffused through channel and the interior of sarcolemma becomes less negative

    lose K and gain Na
  28. repolarization
    • immediately after the depolarization wave passes, Na+ channels are closed and K+ channels open
    • K+ diffused from the cell, restoring the electrical polarity in the sarcolemma
  29. sarcoplasmic recticulum (SR)
    • regulates intracellular calcium levels
    • (like the smooth endoplasmic reticulum)
  30. T tubules
    • penetrate into the cell's interior at each A abnd band junction
    • associate with the terminal ciscternae to form triads
    • they conduct action potentials to the deepest regions of the muscle
    •  and signal the release of Ca
  31. phase 2
    • AP travels across the entire sarcolemma
    • AP travels along T tubules
    • SR releases Ca; Ca binds to troponin; myosin-binding sites (activate sites) on actin exposed
    • myosin heads bind to actin;contracting begins
  32. working(power) stroke
    myosin head pivots and oulls actin filament toward M line
  33. axon terminal does what?
    attaches to neuron
  34. motor unit
    a motor neuron and all the muscle fibers it supplies
  35. contraction of a single motor units does what?
    causes a weak contraction in the entire muscle
  36. muscle that control fine units (fingers and eyes)
    have small motor units
  37. large weight-bearing muscles(thing, hips)
    have large motor units
  38. graded muscle responses
    • variations in the degree of muscle contraction
    • it varies in the # of motor units involved and changing of frequency of stimulation
  39. muscle twitch
    the responses of a a muscle (single motor unit) to a single, brief threshold stimulus
  40. three phases of a muscle twith?
    • latent period
    • period of contraction
    • period of relaxation
  41. latent period
    excitation contraction coupling is taking place( getting ready to contract, very short)
  42. period of contraction
    cross bridges actively form and the muscle shortens
  43. period of relaxation
    Ca is reabsorbed into the SR and muscle tension goes to zero
  44. a single stimulus results in a single contractile reponse
    muscle twitch
  45. wave summation
    frequently delivered stimuli (muscle does not have time to relax) increases contractile force (harder twitch)
  46. tenanus
    • continuous, repeated stimuli results in a maximal sustained contraction
    • the muscle locks up
  47. the force of contraction is precisely controlled by what?
    multiple motor unit summation
  48. recruiment
    as more neurons are activated, more motor units are stimulated to contract
  49. contraction
    refers to the force generated by the formation of myosin across bridges
  50. shortenin
    tension generated by the cross bridge exceeds forces opposing shortening
  51. isometric  contractions
    increasing muscle tension (muscle does not shorten during contraction)
  52. isotonic (concentric) contraction
    decreasing muscle lengh (muscle shortens during contraction)
  53. eccentric contraction
    the muscle contracts as it lengthens
  54. muscle metabolism
    • creatine phospahte 1
    • anaerobic glycolysis 2
    • aerobic respiration 3
  55. muscle fatigue
    the muscle is in a state of physiological inability to contract
  56. what causes muscle fatigue?
    • ATP production fails to keep pace with ATP use
    •  Myosin crossbridges cannot slide and get "stuck" causing contractures
    • the inability to mantain na and K gradients
    • lactic acid accumulates and causes pain
  57. what must happen so muscle can return to a resting state?
    • oxygen reserves must be replenished
    • ATP and CP reserves must be resynthesized
    • lactic acid must be converted to pyruvic acid
    • glycogen must be replaced
  58. oxygen debt
    the extra amount of O2 needed for the muscle to return to a resting state
  59. metabolic stages?
    • glycolytic
    • oxidative
  60. glycolitic
    • fermentation
    • quick but inefficient supply of ATP
    • requires alot of glucose
  61. oxidative
    • slow but alot of ATP
    • response is limited by krebs cycle and ETC
  62. fast muscle fibers
    • White
    • glycolytic
    • need alot of glucose
    • rapid power contractions
  63. slow muscle
    • red
    • oxidative
    • sustained contraction
  64. peristalsis
    wavelike series of contractions that move things in smooth muscle like food

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